Gas turbine engines often have multiple casings, such as an inner and outer wall spaced apart from each other. These spaced apart walls typically include opposing openings to allow for access of inspection devices into the gas path and inner components of the engine. Common inspection devices include borescopes, proximity probes, or laser probes. Known borescope plugs are used to seal the opposing openings in the casings of the gas turbine engine. However, due to the very high temperatures at which gas turbine engines operate, the engine casings undergo thermal growth and expansion. As a result, leakage may still occur when a borescope plug cannot accommodate for these thermal transitions.
Historically, borescope plugs have been non-structural, removable plugs that fill the access hole from the outer case into the gas-path to minimize leakage. Typical borescope plugs can be either solid or flexible. Solid borescope plugs fill the leakage hole but are limited in movement and must be located near the center of thermal growth locations to minimize deflection. Flexible borescope plugs generally have a spring or a thin section to allow radial or axial movement to account for thermal growth. However, many problems persist with the prior art borescope plugs, such as cracking, bending, buckling, installation and withdrawal difficulties.
Thus, there exists a need for a simplified, more reliable borescope plug configuration. This disclosure is directed to solving this need and provides a way to reduce the cost and complexity of a borescope plug assembly.